1. Field of the Invention
The present invention relates to a method of manufacturing an electronic device including a laser diode, a first member supporting the laser diode, and a second member having a waveguide, the first member being positioned with respect to the second member so that light emitted from the laser diode will be incident on the incidence end of the waveguide.
2. Description of the Related Art
With recent improvements in recording density of magnetic recording devices such as magnetic disk drives, there has been a demand for improving the performance of magnetic heads and magnetic recording media. In a magnetic disk drive, a magnetic head is mounted on a slider that flies slightly above the surface of a magnetic recording medium.
To increase the recording density of a magnetic recording device, it is effective to make the magnetic fine particles of the magnetic recording medium smaller. Making the magnetic fine particles smaller, however, causes the problem that the magnetic fine particles drop in the thermal stability of magnetization. To solve this problem, it is effective to increase the anisotropic energy of the magnetic fine particles. However, increasing the anisotropic energy of the magnetic fine particles leads to an increase in coercivity of the magnetic recording medium, and this makes it difficult to perform data writing with existing magnetic heads.
To solve the aforementioned problems, there has been proposed a technology so-called thermally-assisted magnetic recording. The technology uses a magnetic recording medium having high coercivity. When writing data, a write magnetic field and heat are applied almost simultaneously to the area of the magnetic recording medium where to write data, so that the area rises in temperature and drops in coercivity for data writing. The area where data is written subsequently falls in temperature and rises in coercivity to increase the thermal stability of magnetization. Hereinafter, a magnetic head for use in thermally-assisted magnetic recording will be referred to as a thermally-assisted magnetic recording head.
In thermally-assisted magnetic recording, near-field light is typically used as a means for applying heat to the magnetic recording medium. A known method for generating near-field light is to use a plasmon generator, which is a piece of metal that generates near-field light from plasmons excited by irradiation with light. The light for use to generate near-field light is typically guided through a waveguide, which is provided in the slider, to the plasmon generator disposed near the medium facing surface, that is, a surface of the slider that faces the magnetic recording medium.
To supply the light for use to generate near-field light to the waveguide, a laser diode may be secured to the slider to allow laser light emitted from the laser diode to be incident on the incidence end of the waveguide provided in the slider, as disclosed in U.S. Patent Application Publication No. 2011/0228650 A1, for example.
U.S. Patent Application Publication No. 2011/0228650 A1 discloses a thermally-assisted magnetic recording head including a slider having a waveguide, and a light source unit. The light source unit includes a laser diode and a unit substrate for supporting the laser diode. The unit substrate is bonded to the slider, being positioned so that emitted light from the laser diode will be incident on the incidence end of the waveguide. Solder, for example, is used to bond the unit substrate to the slider.
In the process of manufacturing the thermally-assisted magnetic recording head including the laser diode, the unit substrate and the slider as described above, it is important that the unit substrate be accurately positioned with respect to the slider and secured thereto so that emitted light from the laser diode will be accurately incident on the incidence end of the waveguide.
U.S. Patent Application Publication No. 2011/0228650 A1 discloses a positioning and securing method that allows the unit substrate to be positioned with respect to the slider and secured thereto in the following manner. In the positioning and securing method, emitted light from the laser diode is allowed to be incident on the incidence end of the waveguide, the intensity of light emitted from the emitting end of the waveguide is detected, and the unit substrate is positioned with respect to the slider so that the aforementioned intensity becomes maximum. Subsequently, the unit substrate is irradiated with heating laser light that is projected to pass through the unit substrate, so that the solder interposed between the slider and the unit substrate is heated and melted by the heating laser light. After that, the irradiation with the heating laser light is stopped to solidify the solder to thereby allow the unit substrate to be secured to the slider.
Now, problems with the positioning and securing method above will be described. In the method above, there may occur misalignment of the unit substrate with respect to the slider in the process of melting and then solidifying the solder to thereby secure the unit substrate to the slider. The method above thus has the problem that it is impossible to find the misalignment of the unit substrate with respect to the slider, and consequently there is a possibility of occurrence of defective products.
Further, the inventors of this application have found by experiment that irradiating the unit substrate with heating laser light while the laser diode is emitting laser light may later cause irreversible degradation in the optical output of the laser diode or a failure of the laser diode. Thus, the above-described method may lead to deterioration or failure of the laser diode and consequently result in the occurrence of defective products.
The foregoing problems apply not only to the case of manufacturing a thermally-assisted magnetic recording head but generally to the case of manufacturing an electronic device including a laser diode, a first member supporting the laser diode and a second member having a waveguide, where the first member is positioned with respect to and secured to the second member by the above-described positioning and securing method so that light emitted from the laser diode will be incident on the incidence end of the waveguide.